1. Field of Invention
The present invention relates to a unit for mounting an electro-optical device, such as a liquid crystal panel, to a prism, such as a dichroic prism or a polarization beam splitter, and to a projection display device using the same.
2. Description of Related Art
An example of a conventional projection display device relating to the present invention in which an electro-optical device, such as a liquid crystal panel, is mounted to a prism is disclosed, for example, in Japanese Unexamined Patent Publication No. 10-10994. Thus, Japanese Unexamined Patent Publication No. 10-10994 will be briefly described with reference to an exploded view of FIG. 16.
A liquid-crystal-panel unit 70R is mounted to a light-incident surface 72R of a prism composition 72 of a projection display device. The panel unit 70R is composed of an innermost fixed frame body 76 bonded and fixed to the light-incident surface 72R of the prism composition 72, an outermost panel frame body 73 for accommodating and holding a liquid crystal panel 80R, and an intermediate frame body 77 disposed between the fixed frame body 76 and the panel frame body 73. The panel frame body 73 has a first frame body 74 and a second frame body 75, and further holds the liquid crystal panel 80R by sandwiching between these frame bodies 74 and 75.
Engaging projections 77b projected outward from four comers of the intermediate frame body 77 are fitted and bonded into engaging holes 74b formed in four comers of the panel frame body 73 (the first frame body 74 thereof), and a spacer 78 having a substantially triangular prism shape is provided between the intermediate frame body 77 and the panel frame body 73 so as to bond and fix the intermediate frame body 77 and the panel frame body 73.
Process steps for obtaining the above construction will be described hereinbelow with reference to a flow shown in FIG. 17.
That is, the fixed frame body 76 is first located and fixed on the light-incident surface 72R of the prism composition 72 by an adhesive agent (S1). Then, the intermediate frame body 77 is located outside the bonded and the fixed frame body 76, and is fixed by inserting four screws 79 into tapped holes 77a and 76a (S2).
Thereafter, an adhesive agent is charged into the engaging holes 74b that are formed in the first frame body 74 of the panel frame body 73 in which the liquid crystal panel 80R is accommodated and held, and the panel frame body 73 is attached to the intermediate frame body 77 by fitting the engaging projections 77b of the intermediate frame body 77 into the engaging holes 74b (S3).
Next, the liquid crystal panel 80R is turned on in this state (S4), and focus adjustment and alignment adjustment of the liquid crystal panel 80R are performed (S5 and S6). These steps S4 to S6 are performed to adjust the position and the inclination of the liquid crystal panel 80R on the optical axis.
Next, the adhesive agent charged in the engaging holes 74b is hardened to temporarily fix the intermediate frame body 77 and the panel frame body 73 (S7). Thereafter, a shift amount of the position of pixels of the liquid crystal panel 80R is checked (S8). Consequently, when the shift amount is beyond an allowable range (bad), the panel frame body 73 is removed (S13), and the procedure returns to the aforementioned step S3.
On the other hand, when the shift amount is within the allowable range (good), the adhesive agent is applied to the spacer 78 (S9), and the spacer 78 is mounted to a predetermined guide section formed between the temporarily fixed intermediate frame body 77 and the panel frame body 73 (S10). Then,.by hardening the adhesive agent among the spacer 78, the panel frame body 73, and the intermediate frame body 77, the panel frame body 73 is actually fixed to the prism composition 72 (S11).
In the case of the above conventional device, however, the panel frame body is temporarily fixed to the prism after adjusting the position of the liquid crystal panel and then actually fixed at a place different from the temporarily fixed place, resulting in a shift of the position of the liquid crystal panel in an actual fixing step.
In addition, a temporary fixing step differs from the actual fixing step in a bonded section, so that there is a problem in that the operation process is complicated, and the working efficiency is low because a hardening period of the adhesive agent is required for each step.
Also, when the adhesive agent is hardened, the panel frame body is susceptible to displacement due to the contraction of the adhesive agent. However, there is a problem in that the number of bonded sections increases because of the temporary fixing, and hardening of the adhesive agent tends to cause a shift of the position of the liquid crystal panel.
Further, the temporary fixing and the actual fixing are performed at different sections, so that there is a high risk of occurrence of shift of the position of the liquid crystal panel under the influence of expansion or contraction by heat generated by the use of a projection display device. For this reason, there is room for improvement in realizing a projection display device which does not cause a shift of the position of the liquid crystal panel for a long period.
Thus, the present invention proposes a unit which can eliminate a temporary fixing step from steps for fixing an electro-optical device, such as a liquid crystal panel, to a prism and which can mount a panel frame body for accommodating and holding the electro-optical device, such as the liquid crystal panel, to the prism only by a spacer section, and a projection display device using the same to thereby achieve an increase in fixing and positioning accuracy of the electro-optical device, an increase in fixing operation efficiency, and simplification of the fixing operation.
A projection display device is provided having an electro-optical device for modulating light, a prism to which the electro-optical device is mounted, and a projection lens for projecting modulated light. The projection display device may include: a fixed frame plate fixed adjacent to a surface of the prism and a center portion thereof being opened, an electro-optical device frame body for holding the electro-optical device, and a spacer having a plane opposed to the fixed frame plate and a plane opposed to the electro-optical device frame body, and placed between the fixed frame plate and the electro-optical device frame body. The fixed frame plate and the electro-optical device frame body may be bonded and fixed by an adhesive agent via the spacer, and a bonded surface of the fixed frame plate to the spacer may protrude toward the electro-optical device frame body.
In addition, an electro-optical device mounting unit for mounting an electro-optical device for modulating light to a prism, may include: a fixed frame plate fixed adjacent to a surface of the prism and a center portion thereof being opened, an electro-optical device frame body for holding the electro-optical device, and a spacer having a plane opposed to the fixed frame plate and a plane opposed to the electro-optical device frame body, and placed between the fixed frame plate and the electro-optical device frame body. The fixed frame plate and the electro-optical device frame body may be bonded and fixed by an adhesive agent via the spacer, and a bonded surface of the fixed frame plate to the spacer may protrude toward the electro-optical device frame body.
Accordingly, a distance between the effective center of the bonded surfaces of the spacer and the fixed frame plate and the effective center of the bonded surfaces of the spacer and the electro-optical device frame body can be effectively reduced while maintaining the clearance between the prism and the electro-optical device constant, so that the rotational moment exerted on the spacer can be reduced and falling thereof can be prevented during position adjustment operation in fixing the electro-optical device frame body and the fixed frame plate. Therefore, productivity improvement can be achieved. In addition, the stability of the spacer makes it possible to fix the electro-optical device frame body to the fixed frame plate, that is, to actually fix the electro-optical device to the prism using the adhesive agent only to the spacer, whereby bonding places and the number of bonding operations are decreased, and a shift of a position of the electro-optical device can be reduced.
In addition, the bonded surface of the fixed frame plate to the spacer may protrude from the outer periphery of the prism. According to this, a bonding area of the spacer to the fixed frame plate can be increased, so that the spacer can be stabilized to reduce its tendency to fall, and productivity is increased. Further, the stability of the spacer makes it possible to actually fix the fixed frame plate and the electro-optical device using the adhesive agent only to the spacer, whereby bonding places and the number of bonding operations are decreased, and a shift of a position of the electro-optical device can be reduced.
Also, a clearance between a line passing through the center of the bonded surfaces of the fixed frame plate and the spacer and perpendicular to the surface of the prism and a line passing through the center of the bonded surfaces of the electro-optical device frame body and the spacer and perpendicular to the surface of the prism, is equal to or smaller than 2 mm. According to this, the rotational moment exerted on the spacer is significantly reduced during a position adjustment operation in fixing the electro-optical device frame body and the fixed frame plate. Therefore, falling of the spacer can is prevented and productivity improvement can be achieved. Further, the stability of the spacer makes it possible to actually fix the fixed frame plate and the electro-optical device, using the adhesive agent, only to the spacer, whereby bonding places and the number of bonding operations are decreased, and a shift of a position of the electro-optical device can be reduced.
In addition, a width of a frame portion connected to the bonded surface of the fixed frame plate to the spacer is narrower than a width of the surface of the fixed frame plate that is bonded to the spacer. According to this, elasticity (springiness) of the frame portion of the fixed frame plate connected to the spacer is increased, so that the influence of temperature change at the bonded portion of the prism and the electro-optical device can be absorbed by this portion and therefore, a shift of a position based on the temperature change, that is, a shift of pixels, is reduced.
Further, the bonded surface of the fixed frame plate to the spacer is formed by a plate added to a base plate constituting the fixed frame plate. According to this, the stress of the spacer to the adhesive agent can be arbitrarily lightened using a plate whose thickness and size (width and length) can be changed. That is, a member having substantially an intermediate linear expansion coefficient between a linear expansion coefficient of the electro-optical device frame body and a linear expansion coefficient of the prism, is used as the additional plate member, whereby the shift of pixels of the electro-optical device caused by the mutual shift amount due to the temperature change can be effectively relieved. As a specific example of the additional plate, the use of metal, such as iron, may be considered when, for example, the prism is made of glass and the electro-optical device frame body is made of resin.
In addition, by using an additional plate member having a suitable size, stabilization of the spacer can be achieved.